This invention relates to a video data reproducing apparatus and a video data reproducing method, and more particularly to a video data reproducing apparatus adapted for reproducing video data at speed different from that at the time of recording and a video data reproducing method for reproducing video data at speed different from that at the time of recording.
In recent years, there have been increased demands to record or reproduce, at the same time, plural video/audio data from single video/audio data recording/reproducing apparatus and/or to reproduce such data while recording them, etc. unlike conventional VTR (Video Tape Recorder) with realization of multi-channel configuration of information offer by popularization of CATV (Cable Television), etc. In order to satisfy such demands, there have been popularized apparatuses called video server for recording/reproducing video/audio data by using random accessible recording media such as hard disc, etc. The above-mentioned video server is also called AV (Audio and/or Video) server.
Generally, a video server within the broadcasting station is required to have a high transfer rate of necessary data from requirements with respect to picture quality and/or sound quality and to have large capacity for the purpose of recording long time data. In view of the above, there have been made an attempt to use data recording/reproducing apparatus including plural hard disk (hereinafter referred to as HD) units for storing video/audio data and permitted to undergo parallel processing to thereby carry out realization of high speed of transfer rate and large capacity of data, and/or an attempt to further record parity data in advance to thereby have ability to ensure reliability even in the case where either one HD unit is out of order. Thus, even in the case where the required number of channels is changed by the content of program or broadcasting form that the broadcasting station attempts to provide, such an approach is employed to record, in a distributed manner, in advance, material data consisting of plural video/audio data to carry out sending of many channels at the same time, or to reproduce the same material data by many channels in the state where reproduction times are shifted to thereby construct system such as VOD (Video On Demand) or NVOD (Near Video On Demand), etc., thus making it possible to realize multi-channel video server capable of coping with wide variety of use forms.
In the data recording/reproducing apparatus used in such video server, there is used RAID (Redundant Arrays of Inexpensive Disks) technology constituted by plurality of hard disc drives (hereinafter each referred to as HDD) each consisting of plural HDs announced by the article (xe2x80x9cA Case for Redundant Arrays of Inexpensive Disks (RAID)xe2x80x9d, ACM SIGMOND Conference, Chicago, Ill., Jun. 1-3, 1988) disclosed by Patterson, etc. in 1988.
In the above-mentioned article, RAID is classified into five RAIDs of RAID-1 to RAID-5. The RAID-1 is the system of writing the same content with respect to two HDDs. The RAID-3 is the system of recording input data with respect to plural HDDs in the state divided into data of a predetermined length, and generating parity data which is exclusive logical sum of data blocks corresponding to each other of respective HDDs to write it with respect to another HDD. The RAID-5 is the system of enlarging the division unit (block) of data to record one divisional data with respect to one HDD as data block, recording, with respect to HDD, as parity block, result (parity data) obtained by taking exclusive logical sum of data blocks corresponding to each other of respective HDDs and distributing parity blocks to other HDDs. Please reference is made to the above-mentioned article with respect to other RAIDs.
Hitherto, in such a video server, in the case where image recorded on HD is reproduced at a speed lower than one time speed, low speed reproduction is realized in such a manner that, e.g., the same frames are caused to be successively outputted (overlapped).
Moreover, in the case where reproduction image is reproduced at speed higher than one time speed, video data is thinned to take out only a portion of the video data and to discard or abandon other video data to display it.
This is because in the case where reproduction speed is n times speed, i.e., video data corresponding to n frames are reproduced for a time period during which video data corresponding to one frame is reproduced at standard speed, it is difficult to take out video data of one frame or more.
Accordingly, video data of one n-th is reproduced, i.e., only video data of one frame is reproduced and remaining video data of (nxe2x88x921) frames are not reproduced.
FIGS. 1A and 1B are views showing conventional reproduction processing at the time of multiple speed. As shown in FIG. 1A, video data is displayed in order as frame 1, frame 2 . . . frame 9 in the case of one time speed. In the case of three times speed, as shown in FIG. 1B, video data is displayed in order as frame 1, frame 4, frame 7 . . . every fourth frame. It is popularly carried out to carry out such a reproduction image processing thus to display video data.
However, in the case where reproduction speed of video data reproduced as described above is high, all video data are not reproduced. Accordingly, there was the problem that frame to be searched is overlooked.
In addition, since all video data are not reproduced, there is the case where image is different by one frame so that change takes place in the entirety of image. There was the problem that it is impossible to correctly recognize image content.
For example, in the case where object moving at high speed or phenomenon instantaneously changed is recorded only by about 1xcx9c2 frames, there was the case where when video signal in which that image is recorded is reproduced in the state thinned into one n-th, it is impossible to find out object moving at high speed or phenomenon instantaneously changed so that the entire story cannot be understood.
In view of problems of the prior art as described above, an object of this invention is to provide a video data reproducing apparatus and a video data reproducing method capable of recognizing image content even with respect to high speed reproduction.
This invention is directed to a video data reproducing apparatus adapted for reading out data including video data stored with respect to plural non-linear accessible recording media by time slots allocated thereto to output those data, the apparatus comprising: reproduction picture dividing means such that in the case where the video data which has been read out from the recording medium is outputted to the external as n (n greater than 1) times speed video data, when n is integer, it divides output image 1 frame by n, while when n is not integer, it divides output image 1 frame by m (m is integral part of n: n=m. . . . ); and reproduction video generating means for allocating n frames or m frames of the video data which has been read out from the recording medium to the output image 1 frame divided by n or divided by m to generate reproduction image.
In addition, this invention is directed to a video data reproducing method for reading out data including video data stored with respect to plural non-linear accessible recording media by time slots allocated thereto to output those data, the method comprising: a first step such that in the case where the video data which has been read out from the recording medium is outputted to the external as n (n greater than 1) times speed video data, when n is integer, output image 1 frame is divided by n, while when n is not integer, output video 1 frame is divided by m (m is integral part of n: n=m. . . . ), a second step of allocating n frames or m frames of the video data which has been read out from the recording medium to the output image 1 frame divided by n or divided by m to generate reproduction image; and a third step of outputting, as n times speed video data, data indicative of the reproduction image generated at the second step.